## College Physics (7th Edition)

a). (3) $tan^{-1}\frac{w}{d}$ b). $27^{\circ}$
a). $tan r= \frac{w}{d}$ or, $r=tan^{-1}(\frac{w}{d})$ As per the law of reflection, i=r, so, $i=tan^{-1}\frac{w}{d}$, option (3) is the answer. b). $i=tan^{-1}\frac{25cm}{50cm}=tan^{-1}(\frac{1}{2})$ thus, $i=27^{\circ}$